High Chemical Recoveries Research Articles

Determination of 93Zr, 237Np and Th radionuclides in radioactive waste and mineral samples: extension of the method for determination of actinides

A novel method has been developed for the simultaneous determination of difficult-to-measure (DTM) nuclides 93Zr, 237Np, 232Th, 230Th and 228Th using a DGA resin® (containing N,N,N′,N′-tetra-n-octyl-diglycolamide) column for simultaneous separation of Zr and actinides followed by purification of Zr, Np and Th on a TEVA resin® (containing Aliquat 336) column. Samples are destroyed by fusion with sodium hydroxide or by acid destruction using HNO3, HCl and HF. Pre-concentration procedure tailored to the extraction chromatography is based on co-precipitation of Zr and actinides and removal of alumina, silica, iron and calcium. The concentrations of 93Zr, 237Np and Th nuclides are determined by ICP-MS and α spectrometry, respectively. High chemical recoveries (≥ 73%) and separation factors were obtained for Zr, Np and Th both in evaporation concentrates of an NPP and various samples of mineral origin such as soil and concrete. The procedure can be easily combined with the simultaneous separation of other actinides (Pu, Am, U) using the same DGA column that has been described in our previous papers (Cassette et al. in Appl Radiat Isot 68:122–130, 2010 and Groska et al. in J Radioanal Nucl Chem 309(3):1145–1158, 2016).

Optimization of alkali fusion process for determination of I-129 in solidified radwastes by neutron activation

This study determines the optimum temperature for the alkali fusion process used to effectively separate iodine from solidified radwaste attaining low-level 129I by neutron activation. The alkali fusion temperature was adjusted to 120, 200, and 400 °C to approach the optimum conditions associated with a good statistical distribution of the measured 129I data and high chemical recovery yield. Statistical analysis revealed that the optimum temperature of the alkali fusion process was 200 °C, displaying good central tendency and low variance of the measured 129I data, and the respective chemical recovery yields were higher than other temperatures. The optimum fusion condition provides more reliable scaling factors (129I/137Cs) of radwaste.

Rapid method for sequential determination of Pu and Am in soil and sediment samples by sector-field inductively coupled plasma mass spectrometry

New method was developed to analyze Pu and Am sequentially for soil and sediment by inductively coupled plasma mass spectrometry (ICPMS). The developed method uses conc. HNO3 to leach Pu and Am, Fe(OH)3 coprecipitation to remove alkali and alkaline metals, extraction chromatographic separation using UTEVA, DGA and TEVA resins to remove interfering elements (IEs) and separate Pu and Am from each other, and sector field-ICPMS to measure Pu and Am. The analysis of four standard reference materials showed that both Pu isotopes and 241Am were accurately determined by this method, as a result of its excellent decontamination ability of IEs. Especially the high decontamination factor of Pu [DF(Pu), 4.2 × 102] in Am fraction and high DF(Am) (7.0 × 103) in Pu fraction sufficiently eliminated the cross interference between 241Pu and 241Am in ICPMS measurement. In addition, stable and high chemical recoveries were achieved for Pu (71–91%) and Am (70–88%). The low LODs of Pu isotopes, short analytical time (14 h) and high DFs of IEs allows this method to sequentially analyze Pu and Am, for both global fallout and nuclear accident sourced samples.

Method for determination of Pu isotopes in soil and sediment samples by inductively coupled plasma mass spectrometry after simple chemical separation using TK200 resin

Plutonium has been extensively studied in the environment, for the purpose of radiological assessment, environmental behavior study and nuclear emergency response. To determine Pu isotopes in environmental soil and sediment, a novel analytical method was established in this study using a new type of extraction resin, TK200 resin. Firstly an investigation was performed to study the extraction behaviors of Pu, U, Th, Hg, Tl, Pb, Bi and Hf on TK200 resin. On the basis of the results, a new chromatographic procedure was then proposed to separate Pu from the elements that interfere the accurate determination of Pu isotopes by mass spectrometry. Owing to the excellent separation efficiency between Pu and interfering elements (IEs) of the developed procedure, high decontamination factors (DFs) were obtained for IEs, e.g. the DF(U) (>7.5 × 107) was the highest reported value. The separation procedure was finally combined with HNO3 leaching, CaF2/LaF3 coprecipitation and sector field-inductively coupled plasma mass spectrometry (SF-ICPMS) measurement to establish a complete method. The established method was evaluated by analyzing four standard reference materials (soil, sediment), and the results showed that both 239+240Pu activity and 240Pu/239Pu isotopic ratio were accurately determined, with stable and high Pu chemical recoveries (81–91%). The whole analytical method only took about 15 h, and the limits of detection were calculated to be 0.13–0.24 fg g−1 for Pu isotopes (for 2 g soil or sediment), guaranteeing the rapid determination of ultra-trace level Pu in soil and sediment samples.

Determination of plutonium-241 in low-level radwastes using radiochemical separation combined with LSC, alpha spectrometer and ICP-MS

Two kinds of measuring methods were described for the determination of Plutonium-241 in low level wastes in this study. Plutonium isotopes were separated and purified by highly selective UTEVA and TRU resin. LSC, alpha spectrometry, and ICP-MS were applied and compared for determination of Plutonium-241. There is a good agreement with the analytical results and also shows that the different analytical methods have high chemical recovery yields.

Selective Membrane Complexation and Uranium Isotopes Analysis in Tap Water and Seawater Samples.

The complexation of 238U and 234U in tap water and seawater after the use of a selective membrane was examined. At the first step, many ligands were used for original membranes preparation and their yields in uranium analysis were evaluated by X-ray fluorescence, in order to select the ligand with the highest uranium selectivity in water samples. At the second step the new prepared membrane was used for uranium analysis by α-spectrometry. Various factors were tested for a more effective uranium binding such as a membrane's active surface, water sample volume, equilibration time, and stirring during the process. After membrane complexation, uranium was separated by anion exchange and electroplated onto stainless steel plates in order to prepare suitable α-ray sources; these sources were measured by α-spectrometry and gave high chemical uranium recoveries and very good energy resolution spectra. The method can successfully be applied even for relatively small sample volumes and seawater samples.

Rapid determination of Pu isotopes for decommission concrete samples by inductively coupled plasma mass spectrometry

Plutonium is one of the key radionuclides in nuclear decommission. In this study, a rapid method was developed to analyze Pu for concrete samples using total digestion, CaF2/LaF3 coprecipitation, extraction chromatography using TEVA and DGA resins, and ICP-MS measurement. The whole analytical process can be achieved within 2 days, with sufficiently high decontamination factors of interfering elements and high Pu chemical recovery (57–93%). The high throughput (22 samples/2 days) and low LODs (0.008 mBq g−1 for 239Pu and 0.02 mBq g−1 for 240Pu) allow this method to effectively detect low level Pu contamination in concrete samples.

A rapid method for the sequential separation of polonium, plutonium, americium and uranium in drinking water

A new sequential separation method for the determination of polonium and actinides (Pu, Am and U) in drinking water samples has been developed that can be used for emergency response or routine water analyses. For the first time, the application of TEVA chromatography column in the sequential separation of polonium and plutonium has been studied. This method utilizes a rapid Fe+3 co-precipitation step to remove matrix interferences, followed by plutonium oxidation state adjustment to Pu4+ and an incubation period of ~ 1 h at 50–60 °C to allow Po2+ to oxidize to Po4+. The polonium and plutonium were then separated on a TEVA column, while separation of americium from uranium was performed on a TRU column. After separation, polonium was micro-precipitated with copper sulfide (CuS), while actinides were micro co-precipitated using neodymium fluoride (NdF3) for counting by the alpha spectrometry. The method is simple, robust and can be performed quickly with excellent removal of interferences, high chemical recovery and very good alpha peak resolution. The efficiency and reliability of the procedures were tested by using spiked samples. The effect of several transition metals (Cu2+, Pb2+, Fe3+, Fe2+, and Ni2+) on the performance of this method were also assessed to evaluate the potential matrix effects. Studies indicate that presence of up to 25 mg of these cations in the samples had no adverse effect on the recovery or the resolution of polonium alpha peaks.

Rapid method for accurate determination of actinides (U, Th, Pu and Am) in water samples for emergency response

To rapidly assess the contamination of actinides in emergency water, a method was developed to simultaneously analyze U, Th, Pu and Am. The method consists of two steps: extraction chromatographic separation using UTEVA and DGA resins and isotopic determination of actinides by inductively coupled plasma mass spectrometry (ICPMS). The whole analytical procedure takes only 8 h and high chemical recoveries of actinides were obtained. The cross spectral interferences between actinides in ICPMS measurement were sufficiently removed. The accuracy was validated by analyzing IAEA-443 seawater sample. The low limits of detection of actinides allow this method to distinguish low level contamination.

Automated chromatographic separation coupled on-line to ICP-MS measurements for the quantification of actinides and radiostrontium in soil samples

A new protocol for the rapid quantification of actinides (U, Th, Pu, Am and Np) and 90Sr in soil samples has been developed. This protocol includes three steps: (1) an alkaline fusion digestion, (2) an automated separation and (3) an on-line ICP-MS measurement. Eluted fraction containing strontium can be collected to quantify radiostrontium using off-line radiometric techniques. After an optimization of the separation protocol using a design of experiments, excellent figures of merit are achieved. These figures include high chemical recoveries (>80%) for all radionuclides investigated, low quantification limits for actinides and concordance between measured activities and reference values. This protocol allows the automated treatment (sample dissolution included) of up to 10 samples in 24 h.

Sequential determination of 99Tc and 126Sn in radioactive concentrate

Abstract This paper describes a new sequential method using anion exchange resin, which is commercially available from Eichrom Technologies, Inc., for the determination of 99Tc and 126Sn in nuclear waste samples. For the determination of non-actinide radionuclides in radioactive wastes, several methods have been recently introduced. This method is suitable for the separation of radionuclides 99Tc and 126Sn from acidic solutions. Samples after digestion were directly loaded in 2 mol·dm-3 HCl acid on a cation exchange resin and then on an anion exchange. They were eluted with HNO3. After elution, the eluted fractions were measured either by gamma spectrometry on an HPGe detector or liquid scintillation counter with high chemical recoveries for a short period of time. Activity concentrations of 126Sn were below minimum detectable activity (MDA) for each experiment. A new radioanalytical method for the sequential determination of 99Tc and 126Sn in radioactive concentrates has been developed and successfully applied. The main advantage of the method was the time required for the separation of radionuclides, which was only five hours, and single column separation for the determination of these radionuclides, which makes the method very effective and cheap.

Sequential separation method for the determination of uranium and thorium in soil using diamyl amylphosphonate and Aliquat®336 impregnated polymer resins

The accurate and rapid determination of radionuclides in soil is very important to monitor the radioactivity of radionuclides for reduction of hazardous effects to human health. Here, a sequential separation method with a fusion technique was developed to separate uranium and thorium isotopes from a soil sample using polymer resins (UTEVA® and TEVA®) packed columns. The radioactivity of separated U and Th was measured using alpha-particle spectrometry. The developed method was evaluated by assessing the key validation parameters of the selectivity, radioactivity range of linearity, scores for quality control, accuracy, tracer recovery yield, and quantification of uncertainty. The method offered a fast analysis of U and Th isotopes of the soil samples with very high chemical recovery yield and the effective removal of interferences, and demonstrated a satisfactory quality level for the selected criteria of the performance for the method validation. The developed method might be promising for use in a determination of the radioactivity of solid samples containing various interferences.

Pre-concentration of trace levels of rare-earth elements in high purity uranium samples for nuclear forensic purposes

Abstract This paper describes the development of a method for the pre-concentration and analysis of trace-level amounts of rare-earth elements (REE) in high purity uranium (U) samples. The method comprises pre-concentration and subsequent group separation of REEs from the uranium matrix followed by their quantitative determination using inductively coupled plasma mass spectrometry. The achieved detection limit of the method (in the low pg/g range) in combination with the high chemical recovery (around 90%) enabled the investigation of REE patterns in high purity refined uranium oxides. Applying this method one could follow the REE pattern along the entire front-end of the nuclear fuel cycle.

Sequential determination of 93Zr, 94Nb, 99Tc and 126Sn in radioactive waste using anion exchange resin and TEVA® Resin

The paper describes a new sequential method employing anion exchange resin or TEVA® Resin which are commercially available from Eichrom Technologies, Inc. for determination of 93Zr, 94Nb, 99Tc and 126Sn in nuclear waste samples. The method is suitable for the separation of these radionuclides from acidic solutions. Samples after digestion were directly loaded in 0.5 mol L−1 HF acid on cation exchange resin and then on anion exchange or TEVA® Resin. Eluted fractions were measured either by gamma spectrometry on an HPGe detector or liquid scintillation counter with high chemical recoveries during short period of time.

A comparative study of 226Ra determination using total counting and alpha spectrometry in environmental water samples

The quick determination of natural radionuclides is very important in emergency situations, supporting decisions of environmental contamination prevention. A quick methodology for determination of the 226Ra was applied in water samples and the results were compared to those obtained by the conventional method. The technique is based on the microprecipitation of radio barium sulfate and subsequent quantification of 226Ra by alpha spectrometry. The procedure used presented high chemical recoveries and good sensitivity. The main advantage is to obtain the results in 3 days.

Americium and samarium determination in aqueous solutions after separation by cation-exchange

The concentration of trivalent americium and samarium in aqueous samples has been determined by means of alpha-radiometry and UV–Vis photometry, respectively, after chemical separation and pre-concentration of the elements by cation-exchange using Chelex-100 resin. Method calibration was performed using americium (241Am) and samarium standard solutions and resulted in a high chemical recovery for cation-exchange. Regarding, the effect of physicochemical parameters (e.g. pH, salinity, competitive cations and colloidal species) on the separation recovery of the trivalent elements from aqueous solutions by cation-exchange has also been investigated. The investigation was performed to evaluate the applicability of cation-exchange as separation and pre-concentration method prior to the quantitative analysis of trivalent f-elements in water samples, and has shown that the method could be successfully applied to waters with relatively low dissolved solid content.

Rapid fusion method for determination of actinides in fecal samples

A new rapid fusion method for the determination of actinides in fecal samples has been developed at the Savannah River National Laboratory that can be used for emergency response or routine bioassay analyses. If a radiological dispersive device, improvised nuclear device or nuclear accident occur, there will be an urgent need for rapid analyses of environmental, food and bioassay matrices. If an inhalation event occurs and there is confirmed radionuclide activity present via urine analyses of individuals, fecal analyses will typically be required to determine the soluble/insoluble fraction of actinides present as a result of the event to allow a more reliable estimate of radiological dose. The new method for actinides in fecal samples uses accelerated furnace heating, a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation process with stacked TEVA, TRU and DGA resin cartridges. The rapid fusion method provides rugged digestion of any refractory particles present, essential for reliable analysis of actinides in fecal samples. Alpha spectrometry was used to determine the actinide isotopes, but this method can be adapted for assay by inductively-coupled plasma mass spectrometry for actinide isotopes with longer half-lives that have sufficient mass to allow measurement. The method showed high chemical recoveries and effective removal of interferences. The determination of actinides in fecal samples can be performed in less than 12 h in an emergency with excellent quality for emergency samples. The new method, which is much less tedious and time-consuming than other reported methods, can be used for emergency or routine fecal sample analyses. This enables more timely estimates of radiological dose to be performed that utilize soluble/insoluble actinide ratios.

Rapid fusion method for determination of plutonium isotopes in large rice samples

A new rapid fusion method for the determination of plutonium in large rice samples has been developed at the Savannah River National Laboratory (Aiken, SC, USA) that can be used to determine very low levels of plutonium isotopes in rice. The recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid, reliable radiochemical analyses for radionuclides in environmental and food samples. Public concern regarding foods, particularly foods such as rice in Japan, highlights the need for analytical techniques that will allow very large sample aliquots of rice to be used for analysis so that very low levels of plutonium isotopes may be detected. The new method to determine plutonium isotopes in large rice samples utilizes a furnace ashing step, a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation process with TEVA Resin™ cartridges. The method can be applied to rice sample aliquots as large as 5 kg. Plutonium isotopes can be determined using alpha spectrometry or inductively-coupled plasma mass spectrometry (ICP-MS). The method showed high chemical recoveries and effective removal of interferences. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory plutonium particles are effectively digested. The MDA for a 5 kg rice sample using alpha spectrometry is 7 × 10−5 mBq g−1. The method can easily be adapted for use by ICP-MS to allow detection of plutonium isotopic ratios.

Rapid determination of 90Sr in urine samples using AnaLig® Sr-01

This paper describes the use of IBC’s AnaLig® Sr-01 molecular recognition technology product to effectively and selectively pre-concentrate, separate, and recover strontium from urine samples. This method uses two-stage columns separation consisting of two different commercial products Eichrom’s Pre-filter Material and AnaLig® Sr-01 column from IBC Advanced Technologies. This method does not involve co-precipitation of strontium as phosphates and oxalates from urine samples. The new rapid method separates strontium-90 with high chemical recovery.

Rapid determination of 239,240Pu, 238Pu, 241Am and 90Sr in high contaminated samples waste using combined SPE sorbents AnaLig® Pu-02, AnaLig® Sr-01 and DGA® Resin

A rapid separation method has been developed which allows measurement of plutonium, americium and strontium isotopes in the high active sample from CBRN Training and Testing Centre in Zemianske Kostolany (Slovakia) with high chemical recoveries and effective removal of matrix interferences. This method uses different commercial products stacked AnaLig® Pu-02, AnaLig® Sr-01 and DGA® Resin cartridges from IBC Advanced Technologies and Eichrom Technologies. The method allows rapid separation of plutonium, strontium and americium using a single multi-stage column in the vacuum box (cartridge technology) with rapid flow rates to minimize sample separation time. The 239,240Pu, 238Pu and 241Am were determined by alpha spectroscopy, 90Sr was counted on TRICARB 2900 TR by Cerenkov counting of its progeny 90Y.